FFT Algorithm is Clicking

I am trying to test out an FFT algorithm (if you saw my previous post then I was able to get it working, yay!) and I am able to get a nice clean output without any clicking. The moment I try to actually process the spectral data, however, I am left with tons of clicks at regular 4096 sample intervals, the value i have set for my fft size. I imagine there is some inconsistency with the phases or something that makes the fft output not line up smoothly. how can I avoid that and get a smooth output from my plugin?

What I have done with the fft analysis is spectral vocoding (through sidechain input), “squaring” the input (which makes a lossy sound), and spectral gate, removing bins that are too quiet. each of these leaves the audio with these clicks. I have heard of using windowing techniques, but is that necessary?


Absolutely! Process a file in a DAW with your plugin and then look at the rendered waveform afterwords. It will likely have spikes/large discontinuities at the frame boundaries. Windowing and overlapping are typically required on both the FFT input (analysis) AND output (re-synthesis).

Questions like this are better asked on the “DSP and Plugin Development” forum over at KVR. This forum is for iPlug2-specfic questions/issues.